1. Field of the Invention
Embodiments of the present invention generally relate to techniques for mitigating electrode interference in an integrated input device.
2. Description of the Related Art
Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location, and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems, such as touchpads integrated in, or peripheral to, notebook or desktop computers. Proximity sensor devices are also often used in smaller computing systems, such as touch screens integrated in cellular phones or tablet computers.
Proximity sensor devices may include one or more types of electrodes configured for both updating display lines and transmitting input sensing signals. In such shared electrode configurations, in order to increase the amount of time available for performing display updating and/or input sensing, display updating and input sensing may be performed simultaneously during the same time periods. Transmitting input sensing signals on shared electrodes with which display updating is being performed may generate display artifacts and/or negatively impact the accuracy of input sensing. Consequently, as alternative approach, display updating and input sensing may be performed during separate time periods in order to reduce the likelihood of interference between these processes. However, even when display updating and input sensing are performed during separate time periods, charge may remain on and/or leak onto shared electrodes that have recently been driven for display updating, producing interference that negatively impacts input sensing accuracy. Furthermore, when input sensing and display updating are performed at different frequencies, the location(s) of this interference may change with each input sensing cycle, preventing baseline interference values from being determined.
Therefore, there is a need for an improved technique for performing display updating and input sensing in shared electrode proximity sensor devices.